There's no other stethoscope like the ultra-lightweight MDF® ProCardial ERA Lightweight Cardiology Dual Head Stethoscope. This model has been completely reinvented for a lighter feel and convertible chestpiece with three real bells and diaphragms.
I recently purchased this as my second stethoscope for working in the ICU. It was much lighter than it looked but has fantastic sound. I tried it against the more expensive classic cardiology and it beat it for sound and weight.